MdeModulePkg/PiSmmCore: fix bits operation error on a boundary condition

[mirror_edk2.git] / MdeModulePkg / Core / PiSmmCore / HeapGuard.c

diff --git a/MdeModulePkg/Core/PiSmmCore/HeapGuard.c b/MdeModulePkg/Core/PiSmmCore/HeapGuard.c
index 923af93de247d6788958e82701555ca63b9ba5e7..f9657f9baa529c5b03c29106546dfdc66db2d6df 100644 (file)
--- a/MdeModulePkg/Core/PiSmmCore/HeapGuard.c
+++ b/MdeModulePkg/Core/PiSmmCore/HeapGuard.c
@@ -73,7 +73,7 @@ SetBits (
   StartBit  = (UINTN)GUARDED_HEAP_MAP_ENTRY_BIT_INDEX (Address);\r
   EndBit    = (StartBit + BitNumber - 1) % GUARDED_HEAP_MAP_ENTRY_BITS;\r
 \r
-  if ((StartBit + BitNumber) > GUARDED_HEAP_MAP_ENTRY_BITS) {\r
+  if ((StartBit + BitNumber) >= GUARDED_HEAP_MAP_ENTRY_BITS) {\r
     Msbs    = (GUARDED_HEAP_MAP_ENTRY_BITS - StartBit) %\r
               GUARDED_HEAP_MAP_ENTRY_BITS;\r
     Lsbs    = (EndBit + 1) % GUARDED_HEAP_MAP_ENTRY_BITS;\r
@@ -126,7 +126,7 @@ ClearBits (
   StartBit  = (UINTN)GUARDED_HEAP_MAP_ENTRY_BIT_INDEX (Address);\r
   EndBit    = (StartBit + BitNumber - 1) % GUARDED_HEAP_MAP_ENTRY_BITS;\r
 \r
-  if ((StartBit + BitNumber) > GUARDED_HEAP_MAP_ENTRY_BITS) {\r
+  if ((StartBit + BitNumber) >= GUARDED_HEAP_MAP_ENTRY_BITS) {\r
     Msbs    = (GUARDED_HEAP_MAP_ENTRY_BITS - StartBit) %\r
               GUARDED_HEAP_MAP_ENTRY_BITS;\r
     Lsbs    = (EndBit + 1) % GUARDED_HEAP_MAP_ENTRY_BITS;\r
@@ -191,10 +191,14 @@ GetBits (
     Lsbs = 0;\r
   }\r
 \r
-  Result    = RShiftU64 ((*BitMap), StartBit) & (LShiftU64 (1, Msbs) - 1);\r
-  if (Lsbs > 0) {\r
-    BitMap  += 1;\r
-    Result  |= LShiftU64 ((*BitMap) & (LShiftU64 (1, Lsbs) - 1), Msbs);\r
+  if (StartBit == 0 && BitNumber == GUARDED_HEAP_MAP_ENTRY_BITS) {\r
+    Result = *BitMap;\r
+  } else {\r
+    Result    = RShiftU64((*BitMap), StartBit) & (LShiftU64(1, Msbs) - 1);\r
+    if (Lsbs > 0) {\r
+      BitMap  += 1;\r
+      Result  |= LShiftU64 ((*BitMap) & (LShiftU64 (1, Lsbs) - 1), Msbs);\r
+    }\r
   }\r
 \r
   return Result;\r